Stabilization of high resilience polyurethane foam by including in the reaction mixture a polyol containing an effectively dispersed finely divided solid particulate material

ABSTRACT

Polyol compositions containing effectively dispersed particulate material featuring critical dispersion characteristics are used to stabilize foam reaction in high resilience polyurethane foam.

This application is a continuation-in-part of application Ser. No.898,274, filed Apr. 20, 1978, now abandoned which in turn is acontinuation-in-part of application Ser. No. 881,297, filed Feb. 27,1978 now abandoned.

Polyurethane foams commonly are prepared by reacting a polyether polyolwith an organic polyisocyanate in the presence of a blowing agent and areaction catalyst. Various polyether polyols have been employed inmaking such foams; the resulting foam can range in physical propertiesfrom very flexible to fully rigid depending on the hydroxyl number ofthe chosen polyol.

In the art of making flexible polyurethane foam, it is known that byutilizing foam-forming formulations incorporating a highly reactiveorganic polyisocyanate and a high molecular weight polyol having acertain level of primary hydroxyl content, a foam with improvedresilience and other desirable physical properties can be accomplished.Such resulting foams have come to be referred to in the art as "highresilience" foams. Resilient is defined as the ability to return tooriginal shape and dimensions after a deforming force has been appliedand removed from a body. In polyurethane foam technology, the industrygenerally considers "SAC factor" to be the differentiatingcharacteristic between high resilience and conventional foams. This SACfactor, a measure of support provided by cushioning material, is theratio of indent load deflection at 65% deflection to that of indent loaddeflection at 25% deflection (per ASTM D-1564-64T). According to SPIstandards, conventional foams exhibit a SAC factor of about 1.7 to 2.2;high resilience foams have a factor above about 2.2 to about 3.2.

High resilience foams have found widespread application as cushioningmaterial in furniture and bedding. Most significantly, these foams havebeen utilized in the automotive industry for making molded auto seats.The acceptance of these relatively new foams can be attributed to thefact that most already established polyurethane foam techniques can bereadily applied to high resilience foams. However, foam stabilizationand collapsing, one particular area of technology, has been found to bemarkedly non-transferable. Due to the highly reactive nature of thereaction mixture from which the high resilience foams are prepared, suchfoams have been found to exhibit characteristic pre-cure shrinkage.Conventional foam reaction mixture components which serve to stabilizethe composition as it reacts, foams, and solidifies, are ineffective toprevent shrinkage or collapse in high resilience foaming reactions.Moreover, conventional stabilizers actually tend to cause severe voids,splits and shrinkage of the foam product.

Several approaches have been developed to meet the stabilizationrequirements of high resilience foams. For example, U.S. Pat. No.3,880,780 teaches the use of a stabilized foam formulation comprising aselect polyether polyol and polyisocyanate mixture, and an aromaticamine curing agent. In U.S. Pat. No. 3,931,066, a select blend of mainand supplemental polyether polyols is taught to result in a stabilizedfoam product. Select methylene-bridged diaryl polyisocyanates aredescribed in U.S. Pat. No. 3,933,701 as being useful to stabilize highresilience foam from pre-cure collapse shortly after foaming.

In order to achieve foaming stability and enhanced load bearingcharacteristics, it also has become popular to employ "polymer-polyol"processing systems in high resilience foam production. Suchpolymer-polyols, produced from ethylenically unsaturated monomers andpolyols, are exemplified by the materials described in U.S. Pat. Nos.3,383,351; 3,652,639 and 3,823,201. These polymer-polyols commonly aremixed with conventional polyether polyols and used as the startingpolyol reactant.

Another reference, U.S. Pat. No. 4,108,791, discloses that highresilience polyurethane foams with improved foam properties can beaccomplished by preparing the foam from polyols containing an inorganicfiller, having an adjusted pH value of 6-8.5.

It has now been discovered, according to the present invention, that byincorporating a small proportion of effectively dispersed select fineparticulate material into the foam reaction mixture, high resiliencepolyurethane foam can be stabilized against pre-cure collapse orshrinkage, while maintaining other desirable foam properties.

It has previously been known in the polyurethane foam art to employ fineparticulate matter in foam formulations, either as a filler, foreconomic reasons, or to impart certain physical characteristics to thefoam product. For example, it is taught in U.S. Pat. No. 3,640,920 thatrigid, low density insulating foam compositions featuring favorable"freezer stability" can be prepared from a reaction mixture containingabout 0.05 to about 0.5 percent by weight of fine particles, rangingfrom 0.01 to about 250 microns in size.

Another patent, U.S. Pat. No. 3,441,523, describes the use of at least 5percent by weight of particulate filler materials, in the size range ofabout 2 to 25 microns, to prepare filled, flexible, cellular urethaneswithout depreciation of important physical characteristics.

Use of a filler substance commonly results in inferior physicalproperties which offsets the economic advantages of its utility. U.S.Pat. No. 3,150,109 discloses another approach to relieving this problem.By coating common filler pigment materials with an amine alcoholcomposition, it is disclosed that an appreciable amount of filler can beused without significantly affecting the physical properties of lowdensity, open-celled foams.

As mentioned above, U.S. Pat. No. 4,108,791 describes the use of selectinorganic filler particles to improve high resilience flexiblepolyurethane foam properties. This reference teaches that in order toeffectively overcome certain foam deficiencies, the inorganic filleremployed must have a pH of from about 6.5 to about 8.5 and an effectiveparticle size of less than about 7 microns. Various suitable inorganicfillers are listed, including amorphous fumed silica. In order toprepare effective filler material, commercially available fillers, suchas fumed silica, having the specified particle size, are treated with asuitable base or acid, as each situation may dictate, in order to adjustthe pH of the material to between 6.5 and 8.5. When untreated fillermaterials, having a pH outside the specified range, are used inproducing high resiliency foams, it is demonstrated that inferior foamsare formed which exhibit unacceptable problems, such as shrinkage.

Surprisingly, it has now been discovered that rather than pH or initialprimary particle size, the degree of dispersion of the particulatematerial in the reaction mixture is a critical factor in stabilizationeffectiveness. Upon being blended into a polyol composition, fineparticulate material undergoes agglomeration, forming clusters ofparticles markedly larger than the individual particles themselves.Particle agglomerates in a blended polyol composition commonly have beenfound to exhibit effective sizes more than 100 times greater than theinitial size of the individual particles. High resilience foam reactionformulations containing fine particulate material which has not beenselectively blended to ensure a reduced effective dispersed particlesize within the critical limits, as presently defined, fail to avoidunacceptable shrinkage.

According to the present invention, high resilience foam reactionstabilization is accomplished by using a polyol reactant compositioncontaining a small proportion of effectively dispersed fine particulatematerial. Practicing the method of the present invention, suitable fineparticulate material is dispersed in the polyol composition to form adispersion in which the fineness or effective maximum size of theparticles, or particle agglomerates, in the dispersion is less thanabout 75 microns (e.g., per ASTM D-1210-64). Such a dispersion can beaccomplished by using high shear mixers or other blending equipmentwhich effectively eliminates agglomerates or reduces the particleagglomerate size to form a polyol composition featuring dispersedparticle characteristics within the specified critical range.Preferably, the effective particle size in dispersion is less than about50 microns; most preferably about 25 microns or less. An effectivemaximum particle size in dispersion ranging between about 10 to about 20microns has been found to be particularly preferred.

The particulate materials that are utilized according to the presentinvented method are select, finely divided, solid particles that arecompatible with, but insoluble in, the foam reaction mixture.Preferably, the particles have an average primary particle size of lessthan about 75 microns, a surface area of at least about 30 m² /g, andexhibit a bulk density of from about 1 to about 65 lbs./ft.³. Naturallyoccurring materials meeting such physical criteria are not commonlyavailable, but suitable particulate material can be syntheticallyprepared by known methods. Illustrative of particulate materials thatcan be used are: non-metal oxides based on non-metals such as siliconand phosphorus, for example, silicon dioxide, phosphates and phosphites;metal oxides, metal silicates and metal salts, based on metals such asmagnesium, calcium, titanium, barium, aluminum, iron, copper, and zinc;solid organic polymers, such as polystyrene, polyacrylonitrile,polyvinylalcohols, polyvinylchloride and copolymers thereof; solidinorganic polymers, such as polymeric metal alkoxides includingpolyorganosiloxanometalloxanes (e.g., polytriethylsiloxanoaluminoxane,and polytrimethylsiloxanotitanoxane), and silicones; graphite; carbon;and organic pigments, such as common paint pigments, includingphthalocyanines. Particulate carbon (e.g., channel black) and inertmetal and non-metal oxide particles, such as can be produced byhydrolysis of metal and non-metal chlorides in an oxygen-hydrogen flame(e.g., U.S. Pat. Nos. 3,083,115, 3,086,851 and 3,103,495), are preferredstabilizing agents. Particularly preferred are silicon dioxides (e.g.,synthetic amorphous silica, hydrophilic or modified hydrophobic),titanium dioxides and aluminum oxides, such as are commerciallyavailable under the trademark "AEROSIL" from Degussa Corporation, underthe trademark "CAB-O-SIL" from Cabot Corporation and under trademark"SYLOID" from W. R. Grace Co. Such inert oxides featuring an averageprimary particle size of about 0.007 to about 10 microns, having asurface area of about 50 to about 400 m² /g, having a pH ranging fromabout 3 to about 5, and with a bulk density of from about 1 to about 10lbs./ft.³ are most preferred.

According to the present invention, at any step in the preparation ofthe foam ingredients, a small proportion of select fine particulatematerials is blended into the polyol reactant composition in a manner toeffectively disperse the particles as specified. This stabilizing agentmay be added in any proportion effective to achieve the degree ofstabilization desired for a particular formulation. It has been foundpreferable to employ the particulate agent in an amount ranging fromabout 0.1 to about 5.0 percent, based on the total polyol weight. Mostpreferably, about 0.25 to about 1.0 percent of the stabilizing agent isused.

In preparing polyurethane foam pursuant to the present invention, exceptfor the inclusion of a stabilizing proportion of effectively dispersedfine particulate material as defined above, any prior art highresilience foam formulation may be employed. Such formulations comprisevarious combinations of polyether polyols, organic polyisocyanates,foaming agents and reaction catalysts.

The polyether polyol is one that is characterized by (1) a molecularweight of at least about 1,500, (2) a polyfunctional alcohol nucleus,(3) polyoxyalkylene chain segments attached through one end thereof tothe nucleus, and (4) a ratio of primary to secondary hydroxyl end groupsranging from about 1.5:1 to about 5.5:1. This polyether can be preparedby methods generally well known in the art wherein a polyfunctionalalcohol initiator is condensed, in the presence of an alkaline catalyst,first with an alkylene oxide having 3 or more carbon atoms and then withethylene oxide.

The alcohol initiator which is used to prepare the polyether polyol canbe any compound having 2-8 hydroxyl groups. Illustrative are ethyleneglycol, propylene glycol, the butylene glycols such as 1,3-butyleneglycol, the pentane diols such as 1,5 pentane diol, the hexane diolssuch as 1,6-hexane diol, glycerol, trimethylolpropane, sorbitol,pentaerythritol, methyl glucoside, sucrose, mixtures thereof and thelike. It is preferred, however, to employ an aliphatic polyol having2-4, and more preferably 3-4, hydroxyl groups, such as ethylene glycol,propylene glycol, glycerol, trimethylolpropane, sorbitol, and the like.The most preferred initiators are the aliphatic triols such as glyceroland trimethylolpropane.

In preparing the polyether polyol, a polyhydric alcohol initiator asdescribed above is sequentially condensed, in the presence of analkaline catalyst such as potassium hydroxide, first with an alkyleneoxide having 3-8, and preferably 3-4, carbon atoms and then ethyleneoxide. Illustrative of the alkylene oxides which are first condensedwith the alcohol initiator are propylene oxide, butylene oxide,pentylene oxide, mixtures thereof and the like, propylene oxide beingmost preferred. In carrying out the sequential condensation reactions,such amounts of ethylene oxide and higher alkylene oxide are employed soas to provide a polyether having a molecular weight of at least about1,500, and preferably from about 4,000 to about 7,000, and in whichpolyether the ratio of primary to secondary hydroxyl groups is fromabout 1.5:1 to about 5.5:1 and preferably from about 2:1 to about 5:1.

In accordance with a particularly preferred embodiment of the invention,the polyether polyol which is employed in preparing the polyurethanefoam is an oxypropylated, oxyethylated aliphatic triol having amolecular weight of about 4,500-6,600 and a ratio of primary tosecondary hydroxyl groups from about 3:1 to about 4.5:1.

In preparing the foams of the invention, any suitable organicpolyisocyanate, or a mixture of polyisocyanates, may be employed as theisocyanate reactant. Illustrative are toluene diisocyanate, such as the80:20 and the 65:35 mixtures of the 2,4- and 2,6-isomers, ethylenediisocyanate, propylene diisocyanate, methylenebis (4-phenyl)isocyanate, 3,3'-ditoluene-4,4' diisocyanate, hexamethylenediisocyanate, naphthalene-1,5-diisocyanate, polymethylene polyphenylisocyanate, mixtures thereof, and the like. In accordance with aparticularly preferred embodiment of the invention, an isomeric mixtureof 2,4- and 2,6-toluene diisocyanate is employed in which the weightratio of the 2,4-isomer to the 2,6-isomer is from about 60:40 to about90:10 and more preferably from about 65:35 to about 80:20.

The total amount of polyisocyanates that is employed should generally besufficient to provide at least 0.7 NCO group per hydroxyl group in thereaction system, which includes the polyether polyol, as well as anyadditional material and/or foaming agent present in the system. Inpractice a total amount of isocyanate reactant is usually employed as toprovide no more than about 1.25, and preferably about 0.9-1.15 NCOgroups per each hydroxyl group.

Any suitable foaming agent, or mixture of foaming agents, may beemployed in preparing the polyurethane foam. These include inorganicfoaming agents, such as water, and organic foaming agents containing upto 7 carbon atoms, such as the halogenated hydrocarbons and the lowmolecular weight alkanes, alkenes, and ethers. Illustrative organicfoaming agents include monofluorotrichloromethane,dichlorofluoromethane, dichlorodifluoromethane,1,1,2-trichloro-1,2,2,-trifluoroethane, methylene chloride, chloroform,carbon tetrachloride, methane, ethane, ethylene, propylene, hexane,ethyl ether and diisopropyl ether. Water and the low molecular weightpolyhalogenated alkanes, such as monofluorotrichloromethane anddichlorodifluoromethane, are preferred. The amount of foaming agent maybe varied within a reasonably wide range as is well known in the art.Generally, however, the halogenated alkanes, for example, are employedin an amount of about 2-20 parts per 100 parts by weight of thepolyether polyol; and water is employed in an amount of about 1-6 partsper 100 parts by weight of the polyether polyol.

The catalyst employed in preparing the foams of the invention may be anyof the catalysts known to be useful for this purpose, including tertiaryamines, organo-metallic salts, and mixtures of an organo-metallic saltwith 1 or more tertiary amine, the latter being preferred. Typicaltertiary amines include, for example, triethylamine, triethylenediamine, trimethyl-amine, tetramethylene diamine, tetramethylbutanediamine, N-methylmorpholine, N-ethylmorpholine, dimethylpiperazine,trimethylaminoethylpiperazine, dimethylcyclohexylamine, mixtures ofbis(dimethylaminoethylether) and dipropylene glycol such as the 7:3weight ratio mixture which is available commercially under the trademark"Niax A-1", methyldicyclohexylamine, N-cyclohexylmorpholine,dimethylcyclohexylamine, methyldiethanolamine, mixtures ofdimethylcyclohexylamine and 2(3-pentyl)-1-dimethylaminocyclohexane suchas may be purchased commercially under the trademark "Polycat",bis(dimethylaminoethylpropylether), mixtures of triethylene diamine anddipropylene glycol such as the 1:2 and 1:4 weight ratio mixtures whichmay be purchased commercially under the trademarks "Dabco 33LV" and"Dabco 8020", respectively, bis(dimethylaminopropylether), and mixturesof these catalysts. The preferred tertiary amine catalysts aretriethylene diamine, mixtures of bis(dimethylaminoethylether) anddipropylene glycol, dimethylcyclohexamine alone or as a mixture thereofwith 2(3-pentyl)-1-dimethylaminocyclohexame. The tertiary amine catalystis used in a proportion of about 1.0-1.5, and preferably about0.25-0.75, parts per 100 parts by weight of the total polyol which isemployed in preparing the foam.

Typical organo-metallic salts include, for example, the salts of tin,titanium, antimony, aluminum, cobalt, zinc, bismuth, lead, and cadmium,the tin salts, i.e., stannic and stannous salts, being preferred.Illustratively, such salts include the octoates, dilaurates, diacetates,dioctoates, oleates, and neodeconates of these metals, the octoatesbeing preferred. The organo-metallic salt catalyst is used in aproportion of about 0-0.5, and preferably about 0.05-0.2 parts per 100parts by weight of total polyol which is employed in the preparation ofthe foam.

It is preferred in the preparation of the polyurethane foams of theinvention to employ minor amount of a conventional surfactant in orderto further improve the cell structure of the polyurethane foam. Suitablesuch surfactants include, for example, the silicon-based surfactantssuch as the silicons and the siloxaneoxyalkylene block copolymers, allof which are commercially available materials.

Generally, the silicones are employed in a proportion of up to about 0.1parts per 100 parts by weight of the polyether polyol; and thesiloxaneoxyalkylene block copolymers are employed in a proportion of upto about 2 parts per 100 parts by weight of the polyether polyol.

If desired, a curing agent, such as a conventional amine curing agent,may be included in the foam-forming reaction mixture. However, pursuantto the present invention, the use of curing agents is not necessary andtherefore it is preferable to exclude such materials from the reactionmixture.

Various additives can also be employed to provide different propertiesin the polyurethane foam, e.g., fillers such as clay, calcium sulfate,or ammonium phosphate may be added to lower cost and improve physicalproperties. Ingredients such as dyes may be added for color, and fibrousglass, asbestos, or synthetic fibers may be added for strength. Inaddition, plasticizers, deodorants, antioxidants and flame retardantsmay be added.

Foams prepared in accordance with the principles of the presentinvention are characterized by favorable processing characteristics andphysical properties. The foams are substantially open-celled and becometack-free within a relatively short period of time after foamingcessation. Generally ranging in density from about 1.0 to about 5.0,preferably from about 1.7 to about 3.0, pounds per cubic foot, the curedfoams feature a SAC factor in excess of 2.2, generally ranging fromabout 2.3 to about 3.0, and a ball rebound generally greater than about55 percent. These high resilience foams are flexible and soft andexhibit little or no tendency to bottom out. In combination with goodtear strength, tensile strength and elongation, the physical propertiesof the foams of the invention make them desirable for a variety ofcushioning utilities.

The following examples are provided to further illustrate the invention.

EXAMPLE 1 Preparation of Polyol Containing Particulate Dispersion

30 Grams of synthetic fumed silica was added to 600 grams of a polyetherpolyol and mixed for about 10 minutes using a high shear blender havinga blade tip speed of about 4,000 ft./min. to about 8,000 ft./min. Thesilica, obtained commercially under the trademark Cab-O-Sil Grade M-5from Cabot Corporation, is reported to have a pH of 3.5-4.2 and aprimary particle size of 14 millimicrons. The polyether polyol had amolecular weight of about 4,675 and was prepared by end-capping apropoxylated glycerine precursor with 15 moles of ethylene oxide to afinal hydroxyl number of about 36. The effective maximum size of theparticles and/or particle agglomerates in dispersion was measured, usinga grind gauge, per ASTM D-1210-64, to be about 25 microns.

Comparative Example A

To demonstrate the criticality of the degree of dispersion in regard tostabilization effectiveness, a second dispersion was prepared, using thesame components and proportions as in Example 1. In this comparativepreparation, however, a conventional low shear blender, with a blade tipspeed of less than 4,000 ft./min., was used to mix the dispersion forabout 10 minutes. The effective maximum size of the particles and/orparticle agglomerates in dispersion was measured to be greater than 100microns.

EXAMPLE 2 and Comparative Example B

High resiliency polyurethane foams were prepared, using standard foamformulations, but including a proportion of the dispersed silica-polyolconcentrates prepared according to Example 1 and Comparative Example A.Table I outlines the reaction mixture components and proportionsemployed. The reported processing results (pre-cure shrinkage) clearlyindicate the stabilizing effect of employing effectively dispersedsilica according to the present invention, while conventionallydispersed silica fails to accomplish foam stability.

                  TABLE I                                                         ______________________________________                                                                 Comparative                                                      Example 2    Example B                                            ______________________________________                                        Polyol.sup.1  86.5           86.5                                             Product of Ex. 1                                                                            10             --                                               Product of Comp. Ex. A                                                                      --             10                                               Supplemental Polyol.sup.2                                                                   3.5            3.5                                              Diethanolamine                                                                              0.4            0.4                                              Triethylene Diamine.sup.3                                                                   0.53           0.53                                             Water         2.4            2.4                                              Surfactant.sup.4                                                                            1.0            1.0                                              Toluene Diisocyanate.sup.5,                                                   Index         109            109                                              Dibutyltin Dilaurate                                                                        0.1            0.1                                              Foam Processing                                                                             Good, Open     Foam Shrinks                                                   Foam - No Shrinking                                             ______________________________________                                         .sup.1 A polyether triol having a molecular weight of 4,500, prepared by      KOH catalyzed oxyalkylation of glycerin first with propylene oxide and        then with 10 moles of ethylene oxide.                                         .sup.2 A polyether polyol having a molecular weight of 673, prepared by       KOH catalyzed propoxylation of a 3/1 blend of dextrose/glycerin.              .sup.3 Commercially available under the trademark "DABCO 33LV" ,              consisting primarily of triethylene diamine (1/3) and dipropylene glycol      (2/3).                                                                        .sup.4 Commercially available polysiloxane surfactant sold under the          trademark Q25043 from Dow Corning.                                            .sup.5 A mixture of toluene diisocyanate isomers (80:20 mixture of            2,4/2,6isomers).                                                         

EXAMPLES 3-8

A standard gauge of foam stabilizing effectiveness is the "tin range",defined as the range over which the amount of tin catalyst in thefoaming formulation can be varied while maintaining acceptable foamprocessing. The tin catalysts, such as dibutyltin dilaurate, are used toforce the reaction between isocyanate and polyether at such a rate thatviscosity is rapidly increased and the blowing gas is trapped and held.However, too much of an increase in viscosity growth results in a closedcell foam with relatively thick strong cell membranes, and exhibiting avery low air flow and accompanying pre-cure shrinkage. Too little of arate of viscosity growth would cause extensive thinning of the cellmembranes, cell rupture, loss of blowing gas and resultant foamcollapse, settling or splitting.

To permit practical utility, a foam formulation must feature anacceptable "tin range" to avoid frequent foam product failure due toroutine minor fluctuations in the pumped flow rate of the tin catalystfeed stream.

A series of examples were conducted to demonstrate the effect ofdispersed particle size on foam stabilization as represented by tinrange evaluations. Five percent dispersions of Cab-O-Sil Grade M-5 wereprepared as outlined in Example 1, using mixers of varying shear toachieve the desired range of dispersed particle sizes. These dispersedsilica-polyol concentrates were blended with additional polyol toproduce 0.5% concentrations by weight of the silica, based on the totalpolyol weight. Free rise, high resilient foams were prepared, accordingto the formulations reported below in Table II, using standard hand-mixtechniques. The amounts of dibutyltin dilaurate was varied with eachformulation to determine the "tin range", representative of the foamstability achieved through use of each of the silica dispersions. Thereported results illustrate that effective dispersion is a criticalfactor in foam processing stability. The narrow tin range evidenced bydispersed particle sizes greater than 100 microns is impractical andunsatisfactory.

                                      TABLE II                                    __________________________________________________________________________                       Examples                                                                      3    4   5   6   7   8                                     __________________________________________________________________________    Polyol.sup.1       96   →                                                                          →                                                                          →                                                                          →                                                                          →                              Supplemental Polyol.sup.2                                                                        3.5  →                                                                          →                                                                          →                                                                          →                                                                          →                              Dispersed Silica   0.5  →                                                                          →                                                                          →                                                                          →                                                                          →                              Water              2.0  →                                                                          →                                                                          →                                                                          →                                                                          →                              Triethylene Diamine.sup.3                                                                         0.44                                                                              →                                                                          →                                                                          →                                                                          →                                                                          →                              Diethanolamine      0.33                                                                              →                                                                          →                                                                          →                                                                          →                                                                          →                              Surfactant.sup.4   1.0  →                                                                          →                                                                          →                                                                          →                                                                          →                              Toluene Diisocyanate.sup.5, Index                                                                109  →                                                                          →                                                                          →                                                                          →                                                                          →                              Dibutyltin Dilaurate                                                                             Vary →                                                                          →                                                                          →                                                                          →                                                                          →                              Dispersed Phase Particle Size, Microns                                                           >100 75  50  30  25  12.5                                  Tin Range          0.1-0.25                                                                           0.1-0.3                                                                           0.1-0.4                                                                           0.1-0.4                                                                           0.1-0.6                                                                           0.1-0.8.sup.+                         __________________________________________________________________________     .sup.1 A polyether triol having a molecular weight of 4,500, prepared by      KOH catalyzed oxyalkylation of glycerin first with propylene oxide and        then with 10 moles of ethylene oxide.                                         .sup.2 A polyether polyol having a molecular weight of 673, prepared by       KOH catalyzed propoxylation of a 3/1 blend of dextrose/glycerin.              .sup.3 Commercially available under the trademark "DABCO 33LV", consistin     primarily of triethylene diamine (1/3) and dipropylene glycol (2/3).          .sup.4 Commercially available polysiloxane surfactant sold under the          trademark Q25043 from Dow Corning.                                            .sup.5 A mixture of toluene diisocyanate isomers (80:20 mixture of            2,4/2,6isomers).                                                         

EXAMPLE 9 and Comparative Example C

Dispersed particle-polyol concentrates were prepared, using the generalprocedure of Example 1 and Comparative Example A, but employing fineparticulate carbon rather than silica. The carbon, obtained commerciallyunder the trademark Channel Black, Grade FW 200 from DegussaCorporation, is reported to have an average primary particle size of 13millimicrons, a surface area of 460 m² /g and a pH of about 2.

Free rise high resilient foams were prepared, according to the generalmethod of Example 2, using the particulate carbon dispersions within andoutside the scope of the present invention. The formulations and resultsare tabulated below in Table III.

                  TABLE III                                                       ______________________________________                                                                  Comparative                                                      Example 9    Example C                                           ______________________________________                                        Polyol.sup.1   96             96                                              Supplemental Polyol.sup.2                                                                    3.5            3.5                                             Channel Black FW 200                                                                         0.5            0.5                                             Water          2.0            2.0                                             Triethylene Diamine.sup.3                                                                    0.44           0.44                                            Diethanolamine 0.33           0.33                                            Surfactant.sup.4                                                                             1.0            1.0                                             Toluene Diisocyanate.sup.5,                                                   Index          109            109                                             Dibutyltin Dilaurate                                                                         0.1            0.1                                             Dispersed Phase                                                               Particle Size, Microns                                                                       55             >100                                            Foam Processing                                                                              Good, Open Foam                                                                              Shrinks                                         ______________________________________                                         .sup.1 A polyether triol having a molecular weight of 4,500, prepared by      KOH catalyzed oxyalkylation of glycerin first with propylene oxide and        then with 10 moles of ethylene oxide.                                         .sup.2 A polyether polyol having a molecular weight of 673, prepared by       KOH catalyzed propoxylation of a 3/1 blend of dextrose/glycerin.              .sup.3 Commercially available under the trademark "DABCO 33LV", consistin     primarily of triethylene diamine (1/3) and dipropylene glycol (2/3).          .sup.4 Commercially available polysiloxane surfactant sold under the          trademark Q25043 from Dow Corning.                                            .sup.5 A mixture of toluene diisocyanate isomers (80:20 mixture of            2,4/2,6isomers).                                                         

EXAMPLES 10 AND 11

Two dispersed particle-polyol concentrates were prepared, using thegeneral procedure of Example 1, but employing titanium dioxide as thefine particulate material. The titanium dioxide used was obtainedcommercially from Degussa Corporation under the designation Grade P25.This material is reported to have an average primary particle size of15-40 millimicrons, a surface area of about 50 m² /g and a pH value of3-4.

Free rise high resilient foams were prepared, using standard procedures,from the formulations reported below in Table IV. Non-shrinking foamswere accomplished.

                  TABLE IV                                                        ______________________________________                                                         Example 10                                                                             Example 11                                          ______________________________________                                        Polyol.sup.1       95.75      95.75                                           Supplemental Polyol.sup.2                                                                        3.50       3.50                                            Titanium Dioxide, P25                                                                            0.75       0.75                                            Water              2.0        2.0                                             Triethylene Diamine.sup.3                                                                        0.44       0.44                                            Diethanolamine     0.33       0.33                                            Surfactant.sup.4   1.0        1.0                                             Toluene Diisocyanate.sup.5, Index                                                                109        109                                             Dibutyltin Dilaurate                                                                             0.1        0.1                                             Dispersed Phase Particle Size,                                                Microns            60         30                                              Foam Processing    Good, Open Good, Open                                                         Foam       Foam                                            ______________________________________                                         .sup.1 A polyether triol having a molecular weight of 4,500, prepared by      KOH catalyzed oxyalkylation of glycerin first with propylene oxide and        then with 10 moles of ethylene oxide.                                         .sup.2 A polyether polyol having a molecular weight of 673, prepared by       KOH catalyzed propoxylation of a 3/1 blend of dextrose/glycerin.              .sup.3 Commercially available under the trademark "DABCO 33LV", consistin     primarily of triethylene diamine (1/3) and dipropylene glycol (2/3).          .sup.4 Commercially available polysiloxane surfactant sold under the          trademark Q25043 from Dow Corning.                                            .sup.5 A mixture of toluene diisocyanate isomers (80:20 mixture of            2,4/2,6isomers).                                                         

EXAMPLE 12

A dispersed particle-polyol concentrate was prepared, using the generalprocedure of Example 1, but employing aluminum oxide as the fineparticulate material. The aluminum oxide used was obtained commerciallyfrom Degussa Corporation under the designation "Grade C". This materialis reported to have an average primary particle size of 5 to 20millimicrons, a surface area of 100 m² /g and a pH value of 4-5.

A free rise high resilient foam was prepared, using standard procedures,from the formulation outlined in Table V below. A stable, non-shrinkingfoam was obtained.

                  TABLE V                                                         ______________________________________                                                           Example 12                                                 ______________________________________                                        Polyol.sup.1         95.75                                                    Supplemental Polyol.sup.2                                                                          3.50                                                     Aluminum Oxide C     0.75                                                     Water                2.0                                                      Triethylene Diamine.sup.3                                                                          0.44                                                     Diethanolamine       0.33                                                     Surfactant.sup.4     1.0                                                      Toluene Diisocyanate.sup.5, Index                                                                  109                                                      Dibutyltin Dilaurate 0.1                                                      Dispersed Phase Particle Size, Microns                                                             15                                                       Foam Processing      Good, Open                                                                    Foam                                                     ______________________________________                                         .sup.1 A polyether triol having a molecular weight of 4,500, prepared by      KOH catalyzed oxyalkylation of glycerin first with propylene oxide and        then with 10 moles of ethylene oxide.                                         .sup.2 A polyether polyol having a molecular weight of 673, prepared by       KOH catalyzed propoxylation of a 3/1 blend of dextrose/glycerin.              .sup.3 Commercially available under the trademark "DABCO 33LV", consistin     primarily of triethylene diamine (1/3) and dipropylene glycol (2/3).          .sup.4 Commercially available polysiloxane surfactant sold under the          trademark Q25043 from Dow Corning.                                            .sup.5 A mixture of toluene diisocyanate isomers (80:20 mixture of            2,4/2,6isomers).                                                         

EXAMPLES 13-17

A dispersion of a synthetic amorphous silica was prepared by mixing 30 gof the silica with 500 g of a polyether polyol, using a high shearmixer. The silica, obtained commercially under the trademark "SYLOID244" from W. R. Grace Co., had a bulk density of about 7 lbs./ft.³, anaverage primary particle size of about 4 microns, and a surface area ofabout 310 m² /g. The polyether polyol had a molecular weight of about4675 and was prepared by end-capping a propoxylated glycerine precursorwith 15 moles of ethylene oxide. The resulting dispersion, asilica-polyol concentrate was turbid in appearance and had a viscosity,cps @ 250° C., of 2,000.

High resilience, flexible polyurethane foams were prepared usingstandard foam formulations, but including a proportion of thesilica-polyol concentrate, described above. Table VI outlines theingredients and proportions utilized. Comparative Example D exemplifiesa foam prepared without any stabilizing agent; Comparative Example Eexemplifies the prior art stabilization method of including apolymer-polyol component, as discussed in the specification.

In each example, the ingredients were mixed together and poured into asquare cardboard box. A foam product was obtained which was observed forshrinkage or collapse during room temperature curing. After measuringthe core density of each foam, its physical properties weredetermined--compression set, tensile strength, elongation, tearstrength, ball rebound, air flow, and SAC factor (per ASTM D-1564-64T).The results of the physical property testing is tabulated in Table VII,below.

                                      TABLE VI                                    __________________________________________________________________________                  Comparative                          Comparative                              Example D                                                                            Example 13                                                                          Example 14                                                                          Example 15                                                                          Example 16                                                                          Example 17                                                                          Example E                  Reaction Mixture Ingredients                                                                (pbw)  (pbw) (pbw) (pbw) (pbw) (pbw) (pbw)                      __________________________________________________________________________    Polyether Polyol.sup.1                                                                      100     90    70    70    70    70    80                        Polymer-Polyol.sup.2                                                                        --     --    --    --    --    --     20                        Silica Concentrate                                                                          --      10    30    30    30    30   --                         Triethylene Diamine.sup.3                                                                   0.4    0.4   0.4   0.5   0.6   0.6   0.4                        Tertiary Amine Catalyst.sup.4                                                               --     --    --     0.05  0.05  0.05 --                         Surfactant.sup.5                                                                            --     1.0   1.0   --    --    --    --                         Surfactant.sup.6                                                                            1.1    --    --    1.0   1.2   1.2   1.1                        Diethanolamine                                                                              0.8    0.8   0.8   0.8   0.8   0.8   0.8                        Water         2.0    2.0   2.0   2.0   2.0   2.0   2.0                        Dibutyltin Dilaurate                                                                        0.1    0.1   0.1   0.1   0.1    0.15 0.1                        Toluene Diisocyanate.sup.7,                                                   Index         109    109   109   109   109   109   109                        Gel (sec.)    120    130   215   165   150   120   100                        Pre-Cure Foam Shrinkage                                                                     Yes    Yes   No    No    No    No    No                         __________________________________________________________________________     .sup. 1 A polyether triol having a molecular weight of 4,675, prepared by     KOH catalyzed oxyalkylation of glycerin first with propylene oxide and        then endcapped with 15 moles of ethylene oxide.                               .sup.2 Commercially available under the trademark "UC 3128" from Union        Carbide Corporation.                                                          .sup.3 Commercially available under the trademark "DABCO 33LV", consistin     primarily of triethylene diamine (1/3) and dipropylene glycol (2/3).          .sup.4 Commercially available under the trademark "NIAX A1" from Union        Carbide Corporation.                                                          .sup.5 Commercially available polysiloxane surfactant sold under the          trademark "NIAX L5303" from Union Carbide Corporation.                        .sup.6 Commercially available polysiloxane surfactant sold under the          trademark Q25043 from Dow Corning.                                            .sup.7 A mixture of toluene diisocyanate isomers (80:20 mixture of            2,4/2,6isomers).                                                         

                                      TABLE VII                                   __________________________________________________________________________                    Comparative                           Comparative             Physical Properties                                                                           Example D                                                                             Example 13                                                                          Example 14                                                                          Example 15                                                                          Example 16                                                                          Example                                                                             Example                 __________________________________________________________________________                                                          E                       Compression Load Deflection                                                   @ 25% Deflection                                                                              0.26    0.24  0.36  0.34  0.31  0.31  0.35                    @ 65% Deflection                                                                              0.66    0.58  0.86  0.79  0.74  0.74  0.87                    SAC Factor      2.5     2.44  2.4   2.4   2.4   2.4   2.5                     Density, pcf    3.05    2.67  3.14  3.07  2.9   2.96  2.9                     Comp. Set, 75%, C(T)                                                                          4.7     6.1   4.25  3.6   3.5   3.5   4.1                     Tensile, psi    6.7     11.2  11    7.7   8.5   9.0   7.9                     Elongation, %   93      123   137   107   110   120   83                      Tear, pli       0.8     1.2   1.23  1.03  1.0   0.9   1.2                     Ball Rebound, % 61      54    45    64    64    65    65                      Air Flow, cfm   3.03    1.33  1.4   2.0   2.2   2.04  2.9                     __________________________________________________________________________

EXAMPLE 18

The following mixture of foaming ingredients was poured in an aluminummold (6"×6"×6") and heated to 120° F. At the end of foam rise, the moldwas placed in an oven at 300° F. for 6 minutes. The foams were thenremoved and cut in two pieces--to observe its structure. The foamcontaining dispersed particulate stabilizer did not exhibit anyshrinkage, while the comparative example without any stabilizer shrankquite considerably and would be considered not acceptable.

                  TABLE VIII                                                      ______________________________________                                                                 Comparative                                                         Example 18                                                                              Example F                                                           (pbw)     (pbw)                                                ______________________________________                                        Polyether Polyol.sup.1                                                                         100         100                                              Particulate Silica.sup.2                                                                       0.75        --                                               Water            2.5         2.5                                              Catalyst.sup.3   0.27        0.27                                             Catalyst.sup.4   0.09        0.09                                             Diethanolamine   0.8         0.8                                              Surfactant.sup.5 1.0         1.0                                              Dibutyltin Dilaurate                                                                           0.1         0.1                                              Toluene Diisocyanate.sup.6, Index                                                              109         109                                              Foam Stabilization                                                                             No Shrinkage                                                                              Shrinkage                                        ______________________________________                                         .sup.1 A polyether triol having a molecular weight of 4,500, prepared by      KOH catalyzed oxyalkylation of glycerin first with propylene oxide and        then with 10 moles of ethylene oxide.                                         .sup.2 Commercially available under the trademark "CABO-SIL M5" from Cabo     Corporation.                                                                  .sup.3 Commercially available under the trademark "DABCO 33LV", consistin     primarily of triethylene diamine (1/3) and dipropylene glycol (2/3).          .sup.4 Commercially available under the trademark "NIAX A1" from Union        Carbide Corporation.                                                          .sup.5 Commercially available polysiloxane surfactant sold under the          trademark Q25043 from Dow Corning.                                            .sup.6 A mixture of toluene diisocyanate isomers (80:20 mixture of            2,4/2,6isomers).                                                         

We claim:
 1. In a process for preparing a high resilience polyurethanefoam from a reaction mixture comprising:(a) a polyether polyol having amolecular weight of at least about 1,500, a polyhydroxy alcohol nucleushaving a functionality from about 2 to about 8, polyoxyalkylene chainsegments attached to said nucleus, and a ratio of primary to secondaryhydroxyl end groups ranging from about 1.5:1 to about 5.5:1; (b) anorganic polyisocyanate; (c) a foaming agent; and (d) a reactioncatalyst;the improvement characterized by including in said reactionmixture a polyol containing a proportion of an effectively dispersedfinely divided solid particulate material, said particulate materialhaving, prior to dispersion in said polyol, an average primary particlesize of about 0.007 to about 10 microns and a pH ranging from about 3 toabout 5, and further having, in dispersion in said polyol, an effectivemaximum particle size in dispersion of less than about 50 microns. 2.The process of claim 1 wherein said particulate material is dispersed toan effective particle size in dispersion of less than about 25 microns.3. The process of claim 1 wherein said particulate material is added ina stabilizing amount ranging from about 0.1 to about 5.0 percent, byweight, based on total polyol weight.
 4. The process of claim 3, whereinsaid stabilizing amount ranges from about 0.25 to about 1.0 percent. 5.The process of claim 1 wherein said finely divided solid particulatematerial is selected from the group consisting of non-metal oxides,metal oxides, metal silicates, metal salts, solid organic polymers,solid inorganic polymers, carbon, organic pigments, and mixturesthereof.
 6. The process of claim 5 wherein said particulate material isselected from the group consisting of synthetic silicon dioxide,titanium dioxide, aluminum oxide, and mixtures thereof.
 7. The processof claim 6 wherein said particulate material is a synthetic amorphoussilica.
 8. The process of claim 7 wherein said particulate material is asynthetic hydrophobic amorphous silica.
 9. The process of claim 5wherein prior to dispersion into said polyol, said particulate materialhas a surface area of about 50 to about 400 m² /g, and a bulk density ofabout 1 to about 10 lbs./ft.³.
 10. The process of claim 1 wherein saidpolyether polyol reactant has a molecular weight of about 4,000 to about7,000, and a ratio of primary to secondary hydroxyl end groups rangingfrom about 2:1 to about 5:1.
 11. The process of claim 10 wherein saidpolyether polyol reactant is a triol having a molecular weight of about4,500 to about 6,000, and a ratio of primary to secondary hydroxyl endgroups ranging from about 3:1 to about 4.5:1.
 12. The process of claim10 including about 0.1 to about 5.0 percent of said particulate materialselected from silicon dioxide, titanium dioxide, aluminum oxide, andmixtures thereof, said particulate material having a surface area ofabout 50 to about 400 m² /g, and a bulk density of about 1 to about 10lbs./ft.³, and being dispersed to an effective maximum particle size indispersion in the range of about 10 to about 20 microns.
 13. Apolyurethane foam prepared according to the process of claim
 1. 14. Apolyurethane foam prepared according to the process of claim
 9. 15. Apolyurethane foam prepared according to the process of claim 12.